Anomalous spring observations

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We identified observations of plant phenophases in Nature’s Notebook (NN) that were earlier than normal in 2025. We compared 2025 observations with observations collected in 2009-2024 for plants within 100 km and within 1000 m elevation of the plant observed in 2025. We limited analyses to phenophases in 4 phenophase classes: initial vegetative growth (class 1), leaves or needles (3), flowers or cones (6), and open flowers or cones (7), and only evaluated whether an observation was early if there were at least 20 observations for that species and phenophase over 8 or more years between 2009 and 2024.

We classified a 2025 observation as early if it was earlier than 95% of first-of-year observations in 2009-2024, and as an outlier if it was a Tukey outlier (2025 observation earlier than Q1 - 1.5 * IQR). We also noted if the observation was as early or earlier than the earliest date ever recorded in NN for that species, phenophase, and region (earliest).

In the tables below, we list all of the 2025 observations that were considered early or an outlier by phenophase class. Histograms displaying distribution of observations in prior years that were used to assess 2025 potential anomalies are at the bottom of the document.

Table 1: Anomalous observations of initial vegetative growth. ID = individual plant identification number. No. Prior Obs. (Yrs) lists the number of 2009-2024 observations (with the associated number of years) that were used to determine whether a 2025 observation was anomalous or not.

Species	Functional type	ID	State	Lat	Lon	Elev (m)	Date	Early	Earliest	Outlier	No. Prior Obs. (Yrs)
Pacific poison oak	Deciduous broadleaf	270778	CA	37.93	-122.74	74	2025-01-18	Yes	No	No	57 (13)
common snowberry	Deciduous broadleaf	253531	OR	44.94	-123.02	50	2025-01-21	Yes	Yes	Yes	69 (13)
golden currant	Deciduous broadleaf	150497	NM	35.10	-106.68	1508	2025-01-20	Yes	No	No	33 (10)
northern spicebush	Deciduous broadleaf	335285	PA	40.33	-74.94	27	2025-01-17	Yes	Yes	Yes	28 (9)
northern spicebush	Deciduous broadleaf	348399	PA	40.33	-74.94	27	2025-02-19	Yes	Yes	Yes	28 (9)
northern spicebush	Deciduous broadleaf	348400	PA	40.33	-74.94	27	2025-02-19	Yes	Yes	Yes	28 (9)
pecan	Deciduous broadleaf	246701	OK	34.77	-96.66	315	2025-02-07	Yes	No	Yes	38 (8)
red alder	Deciduous broadleaf	78535	CA	37.92	-122.69	0	2025-01-16	Yes	No	No	37 (13)
sugar maple	Deciduous broadleaf	205360	NY	43.01	-78.78	168	2025-02-21	Yes	No	No	133 (9)
sweetgum	Deciduous broadleaf	283106	NC	35.17	-81.06	197	2025-02-04	Yes	Yes	Yes	27 (11)
sweetgum	Deciduous broadleaf	336128	NC	35.28	-81.09	226	2025-02-07	Yes	Yes	Yes	24 (10)
California live oak	Evergreen broadleaf	87340	CA	37.36	-122.13	97	2025-01-21	Yes	No	No	279 (14)
California live oak	Evergreen broadleaf	28811	CA	37.93	-122.74	75	2025-01-26	Yes	No	No	325 (14)
California live oak	Evergreen broadleaf	87339	CA	37.36	-122.13	97	2025-01-30	Yes	No	No	279 (14)

Table 2: Anomalous observations of leaves or needles. ID = individual plant identification number. No. Prior Obs. (Yrs) lists the number of 2009-2024 observations (with the associated number of years) that were used to determine whether a 2025 observation was anomalous or not.

Species	Functional type	ID	State	Lat	Lon	Elev (m)	Date	Early	Earliest	Outlier	No. Prior Obs. (Yrs)
American beech	Deciduous broadleaf	335283	PA	40.33	-74.94	27	2025-01-24	Yes	Yes	Yes	26 (9)
northern red oak	Deciduous broadleaf	204864	NY	43.01	-78.78	168	2025-02-13	Yes	Yes	Yes	39 (10)
northern red oak	Deciduous broadleaf	204866	NY	43.01	-78.78	168	2025-02-13	Yes	Yes	Yes	39 (10)
northern red oak	Deciduous broadleaf	204863	NY	43.01	-78.78	168	2025-02-17	Yes	No	No	39 (10)
northern red oak	Deciduous broadleaf	204858	NY	43.01	-78.78	168	2025-02-18	Yes	No	No	39 (10)
red maple	Deciduous broadleaf	204873	NY	43.01	-78.78	168	2025-02-18	Yes	No	No	63 (8)
red maple	Deciduous broadleaf	204875	NY	43.01	-78.78	168	2025-02-18	Yes	No	No	63 (8)
red maple	Deciduous broadleaf	199342	NY	43.01	-78.78	168	2025-02-21	Yes	No	No	63 (8)
red maple	Deciduous broadleaf	204872	NY	43.01	-78.78	168	2025-02-21	Yes	No	No	63 (8)
sugar maple	Deciduous broadleaf	297758	MA	42.37	-71.15	12	2025-02-03	Yes	Yes	Yes	233 (16)
sugar maple	Deciduous broadleaf	205362	NY	43.01	-78.78	168	2025-02-14	Yes	Yes	Yes	144 (8)
sugar maple	Deciduous broadleaf	205366	NY	43.01	-78.78	168	2025-02-19	Yes	No	Yes	144 (8)
sweetgum	Deciduous broadleaf	336128	NC	35.28	-81.09	226	2025-02-07	Yes	Yes	Yes	23 (8)
Eastern Mojave buckwheat	Drought deciduous broadleaf	31968	CA	34.68	-120.04	357	2025-01-10	Yes	Yes	Yes	28 (10)
blue paloverde	Drought deciduous broadleaf	50745	AZ	32.25	-110.91	746	2025-01-12	Yes	No	No	78 (11)
blue paloverde	Drought deciduous broadleaf	257146	AZ	32.40	-110.98	767	2025-01-21	Yes	No	No	78 (11)
catclaw acacia	Drought deciduous broadleaf	237801	AZ	32.40	-111.00	801	2025-01-10	Yes	Yes	Yes	24 (9)
desert willow	Drought deciduous broadleaf	50750	AZ	32.25	-110.91	746	2025-01-12	Yes	No	Yes	88 (12)
desert zinnia	Drought deciduous broadleaf	278921	AZ	32.40	-111.00	801	2025-01-10	Yes	No	No	46 (8)
honey mesquite	Drought deciduous broadleaf	11431	CA	34.13	-116.04	602	2025-02-03	Yes	No	Yes	24 (12)
ocotillo	Drought deciduous broadleaf	139414	AZ	32.25	-110.91	746	2025-01-26	Yes	No	No	142 (15)
velvet mesquite	Drought deciduous broadleaf	257140	AZ	32.40	-110.98	767	2025-01-21	Yes	No	No	104 (13)
black grama	Graminoid	343755	NM	32.59	-106.84	1330	2025-01-15	Yes	No	No	199 (8)
black grama	Graminoid	343756	NM	32.59	-106.84	1330	2025-01-15	Yes	No	No	199 (8)
black grama	Graminoid	343768	NM	32.59	-106.84	1330	2025-01-15	Yes	No	No	199 (8)

Table 3: Anomalous observations of flowers or cones. ID = individual plant identification number. No. Prior Obs. (Yrs) lists the number of 2009-2024 observations (with the associated number of years) that were used to determine whether a 2025 observation was anomalous or not.

Species	Functional type	ID	State	Lat	Lon	Elev (m)	Date	Early	Earliest	Outlier	No. Prior Obs. (Yrs)
buck-horn cholla	Cactus	117070	AZ	33.60	-111.81	533	2025-02-06	Yes	No	No	79 (9)
Siberian elm	Deciduous broadleaf	63893	NM	35.10	-106.68	1508	2025-01-20	Yes	No	No	54 (11)
arroyo willow	Deciduous broadleaf	29433	CA	37.92	-122.69	0	2025-01-16	Yes	Yes	Yes	43 (13)
arroyo willow	Deciduous broadleaf	275211	CA	38.05	-122.87	25	2025-01-17	Yes	Yes	Yes	43 (13)
black elderberry	Deciduous broadleaf	4194	CA	34.46	-119.71	229	2025-01-22	Yes	No	No	289 (13)
eastern redbud	Deciduous broadleaf	347346	MD	39.03	-77.02	109	2025-01-30	Yes	Yes	Yes	66 (8)
flowering dogwood	Deciduous broadleaf	210868	NC	35.83	-82.55	693	2025-02-13	Yes	No	No	153 (12)
red maple	Deciduous broadleaf	210872	NC	35.83	-82.55	693	2025-01-28	Yes	No	Yes	227 (14)
red maple	Deciduous broadleaf	335280	PA	40.33	-74.94	27	2025-02-01	Yes	Yes	Yes	24 (9)
red maple	Deciduous broadleaf	326716	PA	39.81	-76.35	154	2025-02-03	Yes	Yes	Yes	50 (8)
star magnolia	Deciduous broadleaf	79974	CA	38.38	-122.51	109	2025-02-06	Yes	No	No	25 (8)
sugar maple	Deciduous broadleaf	210871	NC	35.83	-82.55	693	2025-02-10	Yes	Yes	Yes	33 (9)
sweetgum	Deciduous broadleaf	153521	LA	30.05	-89.88	0	2025-01-07	Yes	No	No	28 (8)
bald cypress	Deciduous conifer	127552	LA	30.05	-89.88	0	2025-01-15	Yes	No	No	37 (8)
brittlebush	Drought deciduous broadleaf	199265	AZ	32.34	-110.98	764	2025-01-14	Yes	Yes	Yes	65 (9)
ocotillo	Drought deciduous broadleaf	321434	AZ	33.60	-111.81	533	2025-01-31	Yes	No	No	39 (10)
California live oak	Evergreen broadleaf	28811	CA	37.93	-122.74	75	2025-01-19	Yes	No	Yes	190 (13)
California live oak	Evergreen broadleaf	87340	CA	37.36	-122.13	97	2025-01-21	Yes	No	No	147 (13)
California live oak	Evergreen broadleaf	87339	CA	37.36	-122.13	97	2025-01-30	Yes	No	No	147 (13)
coyotebrush	Evergreen broadleaf	18492	CA	37.98	-122.13	63	2025-01-06	Yes	Yes	Yes	364 (14)
creosote bush	Evergreen broadleaf	246469	AZ	32.37	-110.97	800	2025-01-05	Yes	Yes	Yes	209 (13)
creosote bush	Evergreen broadleaf	102258	AZ	32.24	-110.91	755	2025-01-10	Yes	Yes	Yes	207 (13)
creosote bush	Evergreen broadleaf	50751	AZ	32.25	-110.91	746	2025-01-12	Yes	No	No	207 (13)
creosote bush	Evergreen broadleaf	199258	AZ	32.34	-110.98	764	2025-01-14	Yes	No	No	209 (13)
creosote bush	Evergreen broadleaf	257149	AZ	32.40	-110.98	767	2025-01-19	Yes	No	No	209 (13)
jojoba	Evergreen broadleaf	50747	AZ	32.25	-110.91	746	2025-01-09	Yes	Yes	Yes	90 (13)
jojoba	Evergreen broadleaf	50746	AZ	32.25	-110.91	746	2025-01-12	Yes	No	No	90 (13)
olive	Evergreen broadleaf	347073	CA	37.57	-122.03	12	2025-01-16	Yes	Yes	Yes	29 (10)
redbay	Evergreen broadleaf	151042	MS	30.50	-89.67	18	2025-01-30	Yes	No	No	68 (8)
redbay	Evergreen broadleaf	151043	MS	30.50	-89.67	18	2025-01-30	Yes	No	No	68 (8)
redbay	Evergreen broadleaf	250659	MS	30.40	-88.65	0	2025-02-05	Yes	No	No	86 (8)
wax myrtle	Evergreen broadleaf	283389	LA	30.32	-89.94	3	2025-01-12	Yes	No	No	56 (8)
wax myrtle	Evergreen broadleaf	283390	LA	30.32	-89.94	3	2025-01-12	Yes	No	No	56 (8)
Douglas-fir	Evergreen conifer	28798	CA	37.93	-122.74	74	2025-01-18	Yes	No	No	31 (13)
eastern redcedar	Evergreen conifer	84087	NY	41.75	-74.12	89	2025-01-29	Yes	Yes	Yes	38 (11)
blue oak	Semi-evergreen broadleaf	87379	CA	37.36	-122.13	112	2025-01-28	Yes	Yes	Yes	36 (12)
blue oak	Semi-evergreen broadleaf	53668	CA	37.36	-122.13	112	2025-01-30	Yes	Yes	Yes	36 (12)

Table 4: Anomalous observations of open flowers or cones. ID = individual plant identification number. No. Prior Obs. (Yrs) lists the number of 2009-2024 observations (with the associated number of years) that were used to determine whether a 2025 observation was anomalous or not.

Species	Functional type	ID	State	Lat	Lon	Elev (m)	Date	Early	Earliest	Outlier	No. Prior Obs. (Yrs)
star magnolia	Deciduous broadleaf	79974	CA	38.38	-122.51	109	2025-02-06	Yes	No	No	27 (9)
brittlebush	Drought deciduous broadleaf	246477	AZ	32.37	-110.97	800	2025-02-15	Yes	No	No	67 (10)
California live oak	Evergreen broadleaf	270774	CA	37.93	-122.74	75	2025-01-12	Yes	Yes	Yes	141 (13)
California live oak	Evergreen broadleaf	87339	CA	37.36	-122.13	97	2025-01-21	Yes	No	No	107 (13)
coyotebrush	Evergreen broadleaf	18492	CA	37.98	-122.13	63	2025-01-06	Yes	Yes	Yes	334 (14)
creosote bush	Evergreen broadleaf	102258	AZ	32.24	-110.91	755	2025-01-10	Yes	Yes	Yes	368 (16)
creosote bush	Evergreen broadleaf	50751	AZ	32.25	-110.91	746	2025-01-12	Yes	No	Yes	368 (16)
creosote bush	Evergreen broadleaf	199258	AZ	32.34	-110.98	764	2025-01-14	Yes	No	Yes	369 (16)
jojoba	Evergreen broadleaf	199269	AZ	32.34	-110.98	764	2025-01-14	Yes	Yes	Yes	86 (13)
olive	Evergreen broadleaf	347073	CA	37.57	-122.03	12	2025-01-16	Yes	Yes	Yes	20 (8)
Douglas-fir	Evergreen conifer	28798	CA	37.93	-122.74	74	2025-01-18	Yes	No	No	24 (11)

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Figure 1: Map of early phenological observations. Green leaves denote early observations of initial vegetative growth and/or leaves or needles, and purple flowers denote early observations of flowers or cones and/or open flowers or cones. Circles delineate the areas containing plants observed in prior years that were used for comparison. Blue shading indicates areas that were cooler than normal as of 2025-03-06 (>40 deg F below 30-year normals for accumulated growing degree days with 32 deg F base); orange shading indicates areas that were warmer than normal as of 2025-03-06 (>40 deg F above 30-year normals). Clicking on an icon will display the species name and individual plant ID.

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Figure 2: Initial vegetative growth. Distributions of first-of-year observations in 2009-2024 that were used to assess whether a 2025 observation (red vertical line) was unusually early.

Figure 3: Leaves or needles. Distributions of first-of-year observations in 2009-2024 that were used to assess whether a 2025 observation (red vertical line) was unusually early.

Figure 4: Flowers or cones. Distributions of first-of-year observations in 2009-2024 that were used to assess whether a 2025 observation (red vertical line) was unusually early.

Figure 5: Open flowers or cones. Distributions of first-of-year observations in 2009-2024 that were used to assess whether a 2025 observation (red vertical line) was unusually early.